I would like to add something to the above.
It is unlikely that your elevated total bilirubin is due to a sample error since you've had it consistently elevated throughout out a 2 year period.
However, I do not feel that you should worry about it. There is a condition called Gilbert's syndrome in which there is consistently high levels of total bilirubin without elevation of any other liver markers. This is a very common and completely benign condition (often genetical) and will not cause any additional problems for you in the long run. More often then not there are no other symptoms of this condition besides elevated bilirubin.
If you wish to read up on this condition, below is the link:
You might also consider getting an ultrasound of the liver done. Most likely it will come back completely normal, but this will help you ease your mind.
Please let me know if you have any questions or need any clarification. I will be glad to assist.